Lysyl oxidase activity contributes to collagen stabilization during liver fibrosis progression and limits spontaneous fibrosis reversal in mice

FASEB J. 2016 Apr;30(4):1599-609. doi: 10.1096/fj.14-268425. Epub 2015 Dec 23.

Abstract

Collagen stabilization through irreversible cross-linking is thought to promote hepatic fibrosis progression and limit its reversibility. However, the mechanism of this process remains poorly defined. We studied the functional contribution of lysyl oxidase (LOX) to collagen stabilization and hepatic fibrosis progression/reversalin vivousing chronic administration of irreversible LOX inhibitor β-aminopropionitrile (BAPN, or vehicle as control) in C57Bl/6J mice with carbon tetrachloride (CCl4)-induced fibrosis. Fibrotic matrix stability was directly assessed using a stepwise collagen extraction assay and fibrotic septae morphometry. Liver cells and fibrosis were studied by histologic, biochemical methods and quantitative real-time reverse-transcription PCR. During fibrosis progression, BAPN administration suppressed accumulation of cross-linked collagens, and fibrotic septae showed widening and collagen fibrils splitting, reminiscent of remodeling signs observed during fibrosis reversal. LOX inhibition attenuated hepatic stellate cell activation markers and promoted F4/80-positive scar-associated macrophage infiltration without an increase in liver injury. In reversal experiments, BAPN-treated fibrotic mice demonstrated accelerated fibrosis reversal after CCl4withdrawal. Our findings demonstrate for the first time that LOX contributes significantly to collagen stabilization in liver fibrosis, promotes fibrogenic activation of attenuated hepatic stellate cells, and limits fibrosis reversal. Our data support the concept of pharmacologic targeting of LOX pathway to inhibit liver fibrosis and promote its resolution.-Liu, S. B., Ikenaga, N., Peng, Z.-W., Sverdlov, D. Y., Greenstein, A., Smith, V., Schuppan, D., Popov, Y. Lysyl oxidase activity contributes to collagen stabilization during liver fibrosis progression and limits spontaneous fibrosis reversal in mice.

Keywords: BAPN; CCl4; collagen cross-linking; hepatic stellate cells.

MeSH terms

  • Aminopropionitrile / administration & dosage
  • Aminopropionitrile / pharmacology
  • Animals
  • Carbon Tetrachloride
  • Collagen / metabolism*
  • Collagen Type I / genetics
  • Collagen Type I / metabolism
  • Disease Progression
  • Fibrosis
  • Gene Expression / drug effects
  • Hepatic Stellate Cells / drug effects
  • Hepatic Stellate Cells / metabolism
  • Injections, Intraperitoneal
  • Liver / drug effects
  • Liver / metabolism*
  • Liver / pathology
  • Liver Cirrhosis, Experimental / chemically induced
  • Liver Cirrhosis, Experimental / metabolism*
  • Liver Cirrhosis, Experimental / prevention & control
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Male
  • Matrix Metalloproteinase 13 / genetics
  • Matrix Metalloproteinase 13 / metabolism
  • Mice, Inbred C57BL
  • Microscopy, Confocal / methods
  • Protein-Lysine 6-Oxidase / antagonists & inhibitors
  • Protein-Lysine 6-Oxidase / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tissue Inhibitor of Metalloproteinase-1 / genetics
  • Tissue Inhibitor of Metalloproteinase-1 / metabolism
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism

Substances

  • Collagen Type I
  • Tissue Inhibitor of Metalloproteinase-1
  • Transforming Growth Factor beta1
  • collagen type I, alpha 1 chain
  • Aminopropionitrile
  • Collagen
  • Carbon Tetrachloride
  • Protein-Lysine 6-Oxidase
  • Matrix Metalloproteinase 13